Is there a difference between the throttle position sensor and the throttle body. The car in question is a 1997 Volkwagen Jetta.
The throttle position sensor is mounted on the throttle body. The throttle body is where air is introduced into the engine. In the throttle body is the throttle plate. This opens and closes depending if you’re on the gas or off the gas. Attached to the throttle plate shaft is the throttle position sensor. This sensor tells the computer the position of the throttle.
Auto Zone has the throttle position sensor for your Jetta for only $149. Do you have a cheaper guess? For that price, you could pay someone to test the one on the car; or, get the Haynnes repair manual, a digital electrical multimeter ($25 at Walmart), and, following those instructions in the Haynes, find out for sure, whether, or not, the throttle position sensor is defective.
Yes, there is a difference, and a rather substantial one. I cannot explain this difference any better than Tester already has.